The invention relates to a tensioning apparatus for a lashing strap. More particularly, the invention relates to a tensioning apparatus of the type that includes a frame for fixing one end of the lashing strap between its side walls, a spindle supporting a tensioning lever that is fixable so as to be secured against rotation for winding up the lashing strap from its other end, the spindle being rotatably mounted on the frame so as to bridge the space between its side walls, and a ratchet securing mechanism effective between the frame and the spindle for securing against rotation in the opposite direction the rotary position attained on the basis of the operation of the tensioning lever. A tensioning apparatus of this type is disclosed, for example, in German Patent 2,895,227.C2.
Such tensioning apparatuses serve as tensioning and tie-down devices for actual straps, with lashing straps constituting a preferred embodiment of the tensioning and tie-down means, which may also be in the form of chains, steel cables, ropes or the like. With such lashing straps, goods to be transported are charged with the necessary lashing tension to secure their position on transporting aids or transporting means, for example the beds of trucks.
For this purpose, a tensioning apparatus of the above-mentioned type is customarily provided with a frame which serves as the basic body and which may be fixed to the load-carrying surface. Usually, however, the frame housing is configured as a strap holding arm in such a manner that the fixed end of the lashing strap is fixed to a free end of the frame, for example by means of a holding pin, while at the same time a spindle that is coupled with a ratchet device is provided at the opposite free end of the frame. Such ratchet mechanisms are generally known (see Brockhaus Enzyklopadie [Brockhaus Encyclopedia], 17th Edition, Volume 17, page 714, published by Brockhaus, Wiesbaden, 1973.
After encircling the load to be secured, the loose end of the lashing strap is pulled through a slot, which usually passes through the wind-up spindle diametrally and over its entire length, as far as this is possible without resistance. Then the wind-up spindle is rotated by pivoting a tensioning lever back and forth. The tensioning lever drives an externally toothed ratchet wheel of the ratchet device in the tensioning direction of the wind-up spindle, so that the lashing strap is wound around the wind-up spindle which acts in the manner of a wind-up reel and is thus charged with an increasing lashing tension.
The conventional tensioning apparatuses are constructed in such a manner that, in the rest state and in the final load securing state, respectively, the tensioning lever takes on a position in which it is parallel to the frame. In order to tension the lashing strap, that is to generate the necessary torque to be transferred to the wind-up spindle, the tensioning lever is pivoted away from the frame until the frame and the tensioning lever form approximately a 90.degree. angle whose apex lies approximately in the center axis of the wind-up spindle The lashing strap is tensioned as described above by a back-and-forth movement of the tensioning lever between the rest position and the 90.degree. position. For this purpose, the teeth of the ratchet wheel are provided with mutually asymmetrical flanks and are oriented in such a manner that a catch that is displaceable at the pivot arm lockingly engages in the teeth in one pivoting direction of the pivot arm and, by its pivoting movement, turns the ratchet wheel together with the wind-up spindle that is kinematically coupled with it in the tensioning direction (load stroke), while in the opposite pivoting direction, the catch slides over the usually rounded rear flanks of the teeth (no-load stroke). Consequently, the back and forth movement of the pivot lever is always composed of a load stroke and a no-load stroke. If the load stroke is effected by pulling the tensioning lever to perform a pivoting movement from the 90.degree. position toward the frame into the rest position, one speaks of a pull ratchet. If, however, the load stroke is effected by pushing the tensioning lever from the rest position into the 90.degree. position away from the frame housing, one speaks of a push ratchet.
The major drawback of being able to tension such pull and push ratchets in only one direction is evident. Another drawback in connection with permanently mounted tensioning apparatuses is that they may be mounted in an ergonomically favorable manner for right-handed operators but not for left-handed operators.
For the use of such tensioning ratchets it has been found to be useful for the operator lean on the tensioning lever of the apparatus so as to use the resulting force of his body weight to transfer the necessary torque by way of the tensioning lever to the tensioning apparatus. Consequently, the one-sidedness of the direction of rotation of the tensioning apparatus may be a drawback depending on the momentary position of the operator relative to the apparatus.
Another drawback is that it is necessary right from the start, when a tensioning apparatus is initially acquired, to settle on a certain tensioning direction. Moreover, care must always be taken, when tying down the load to be secured, to consider which final position the apparatus will ultimately take up.